samples/bpf/parse_simple.c

Source file repositories/reference/linux-study-clean/samples/bpf/parse_simple.c

File Facts

System
Linux kernel
Corpus path
samples/bpf/parse_simple.c
Extension
.c
Size
1308 bytes
Lines
50
Domain
Support Tooling And Documentation
Bucket
samples
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

struct eth_hdr {
	unsigned char   h_dest[ETH_ALEN];
	unsigned char   h_source[ETH_ALEN];
	unsigned short  h_proto;
};

SEC("simple")
int handle_ingress(struct __sk_buff *skb)
{
	void *data = (void *)(long)skb->data;
	struct eth_hdr *eth = data;
	struct iphdr *iph = data + sizeof(*eth);
	struct udphdr *udp = data + sizeof(*eth) + sizeof(*iph);
	void *data_end = (void *)(long)skb->data_end;

	/* single length check */
	if (data + sizeof(*eth) + sizeof(*iph) + sizeof(*udp) > data_end)
		return 0;

	if (eth->h_proto != htons(ETH_P_IP))
		return 0;
	if (iph->protocol != IPPROTO_UDP || iph->ihl != 5)
		return 0;
	if (ip_is_fragment(iph))
		return 0;
	if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT))
		return TC_ACT_SHOT;
	return 0;
}
char _license[] SEC("license") = "GPL";

Annotation

Implementation Notes